This group studies how organisms sense environmental signals and transduce the signals into changes in gene expression and cell physiology. The group has continued their characterization of the Escherichia coli response to oxidative stress. Two regulators are central to the response to hydrogen peroxide: OxyR, a 34 kDa transcriptional activator which is switched on by oxidation, and OxyS, a novel 109 nucleotide RNA regulator which acts as an activator and repressor of gene expression. The group has defined functional domains within the OxyR protein and elucidated the nature of OxyR-DNA recognition. Additional OxyS-regulated genes as well mutations affecting regulation by OxyS have been characterized. Using Arabidopsis thaliana as a model system, the group has also identified mutants defective in their developmental response to blue light.